In general, a drilling apparatus for boring a hole into the ground is based on a technique of simply circulating a bit or a screw, or a technique of not only circulating a bit or a ball cutter but also pressurizing the same. According to the latter method, the ground is bored by rotating a bit installed at an end portion of a rod and air-suctioning circulating water and cloven rocks through a drill rod pipe, followed by hoisting the rocks to the surface of the ground. This method is essentially employed in a large-diameter cast-in-place and a top-down method for a foundation work.
Meanwhile, in the course of performing a drilling work, the drilling apparatus mounts or separates a rod having a bit installed thereat or length-extending rods as a drilling depth increases. During a mounting operation of the length-extending rods, a rod for drilling the ground is connected to a driving shaft installed at a head part. In the mounting operation of the length-extending rods, since suspending the rod using a separate crane and setting the same are manually performed, the number of works required in mounting rods may increase.
In the conventional drilling apparatus, in order to smoothly perform the rod mounting operation, a cartridge is installed at a lateral surface of a lid, and the cartridge is rotated toward a lower portion of the driving shaft of the head part to exchange rods or to store withdrawn rods.
The conventional drilling apparatus requires separate equipment for mounting rods on the cartridge. In addition, a considerable time is required in mounting rods on the cartridge. In addition, when a deep hole is drilled, the number of rods required may increase. However, since the number of rods loaded into the cartridge is limited, it is quite difficult for the conventional drilling apparatus to be employed to boring a deep hole.
In light of the foregoing, in order to bore a relatively deep hole, multiple rods are carried using a truck to a construction site where the drilling work is performed. The rods are lifted from the truck using an auxiliary crane to then be mounted on the driving shaft of the head part installed at the lid. Thus, the rod mounting efficiency cannot be improved.